The objective of this project is to understand the metabolism of the plant hormone indole acetic acid. Inputs to the endogenous free indole-3-acetic acid (IAA) pool are: [1] IAA synthesis: and [2] IAA conjugate hyrolysis. The outputs from the free IAA pool are: [3] IAA oxidation: [4] IAA conjugate synthesis: [5] IAA use in growth. At least two biosynthetic pathways, one involving, one not involving tryptophan, contribute to [1]. We have made progress on sequencing IAA-glucose and IAA-myo-inositol hydrolase as contributors to [2]. The mechanism of IAA oxidation in maize is known but its role in IAA output [3] is unknown. [4] The gene for 1-0-IAA-glucose synthesis has been cloned and sequenced and the enzyme catalyzing IAA-inositol synthesis is being sequenced. [5]